The present invention relates to a steering device, and relates in particular to a telescoping type steering device to telescopically adjust the position of the steering wheel by way of an upper column and a lower column that engage along the axis in a sliding motion; or a steering device to absorb the impact load during a secondary collision by way of a collapsing movement towards the front of the vehicle chassis, and also a steering device including a rolling bearing to axially support a rotatable steering shaft.
The rolling bearing axially supporting the rotatable steering shaft has low frictional resistance and this frictional resistance is stable so that the steering wheel operation is very smooth. The roller bearing however possesses a small vibration absorption characteristic so vibrations in the wheel axis due to bumps on the road surface during high-speed driving are transmitted unchanged to the steering wheel, to cause tiny vibrations along the upward/downward and rotational directions of the steering wheel so the roller bearing has the problem that handling stability becomes worse.
The steering device in Japanese Unexamined Patent Application Publication No. Hei9(1997)-303387 applies frictional resistance to the steering shaft by mounting a plain bearing via an elastic piece between the inner circumferential surface of the column and outer circumferential surface of the steering shaft to absorb steering wheel vibrations and improve handling stability. However, the steering device in Japanese Unexamined Patent Application Publication No. Hei9 (1997)-303387 is designed for use with plain bearings and cannot be used with roller bearings.
The steering device in Japanese Unexamined Patent Application Publication No. 2005-53292 applies frictional resistance to the steering shaft by way of a cylindrical friction application member mounted by way of an O-ring on the rear end outer circumferential surface of the steering shaft axially supported by the rolling bearing to allow rotation at the front end of the steering shaft, and absorbs vibration applied to the steering wheel in order to improve handling stability. However the steering device of Japanese Unexamined Patent Application Publication No. 2005-53292 is not easily adaptable to steering devices in which the upper column and lower column engage along the axis in a sliding motion.